car subwoofer to phone

Rahul_23

Distinguished
Sep 24, 2010
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18,510
Hi,
I got these sony Xplode car subwoofers they are like a decade old, my cars music system got stolen last year, so now I am trying to connect these two subs to my phone via a 3.5mm jack.

What I did, is I took one of my old earphones and cut it to get the 3.5mm jack I needed, and joined the two subs in parallel, and directly connected to my car battery.

I am not certain but I guess they are 4ohm subs so connecting them in parallel makes them 2ohms.
My question is should I use an amp or can I directly connect this to my phone, coz one of my friend told me this arrangement will cause a considerable amount of current through the 3.5 jack hence damaging it.
 

BrandonYoung

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Oct 13, 2014
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4,610
Use an amplifier.
<phone>--<audio signal cable>--<amp --<battery>>--<speakers>

It may be better to wire in series vs parallel for a 8 (+/-) ohm load to the amp (make sure your amp is 2ohm stable if going parallel).

Phones have a difficult time driving unamplified 5 watt speakers, wiring your subs to your headphone out on your phone will not provide enough wattage to do anything. If you hear anything at all, it will be very very quiet. You -NEED- an audio amplifier of some type.

I'm not sure how you would do it, but if you connect your subs directly to a car battery, you will destroy your subs for sure unless perhaps they are incredibly high wattage.

In the concert audio business, we would connect a 9v battery to speakers (75-2000 watt) to see if they work. This forces the cone in or out depending on the polarity. If you attempted this with a car battery, the speaker would fully extend in, or out, then the diaphragm would probably fuse itself to the driver rendering your speaker useless, then it would probably catch fire or melt the insulation off your cables. Sounds like a fun experiment, but I would not advise this if you hope to use your speakers in the future.
 

Rahul_23

Distinguished
Sep 24, 2010
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18,510
I didn't connect anything yet.
I will upload pics of my subs tonight, they seem to be of the same size(maybe they are a bit larger) as in the video.
So how big an amp are we talking about here can it be built or do I have to spend bucks on it?